Once again in my proofreading I have come across a mis-use of the words classic and classical. If the word classic is used as an adjective e.g. a classic solution, then you can’t use classical because classical refers to the times of the classics (we are talking Greek classics here). The same applies to historic and historical. A historic step means a very memorable step. A historical step means a step that took place some time in the historical past.If you don’t like my explanation, you can also look up the difference here.